s such as
this, the retarding velocity must be calculated with a nicety many
hours in advance.

We hung now, very nearly poised, within some forty thousand miles of
the surface of the Moon. Bleak and cold, sharply black and white, it
hung in a gigantic crescent in advance of our bow. The Sun, whose
attraction I had ceased using some hours back, was visible sharply to
one side now. Its great gas streams of giant flame licked up into the
blackness of the firmament. The sunlight caught the lunar mountains
with a white glare, and left the valleys black with shadow; moonlight
and the mingled sunlight painted our bow. Behind our stem the great
disk of Earth hung somber and glowing.

And everywhere else was the great black enclosing firmament. The stars
blazed with a new white glory never seen through the haze of an
atmosphere. Like a little world in the vastness of this awesome void,
we hung poised.

Grantline came into the turret. "I've got everything ready, Gregg. By
the gods, once you can lay telescope upon that accursed enemy ship,
I'm ready to open fire on it."

"Good," I said.

But the thought of hurling our bolts at this enemy ship had struck
terror into my heart for hours past. I was convinced that the three
who in all the world were dearest to me--Anita, Venza, and Snap--were
upon that enemy vessel.

Grantline asked, "Are you going closer to the Moon?"

"No."

"The ship couldn't be between us and the Moon. Waters and I have been
in the helio room for the past hour, searching with the 'scope there.
Nothing doing, Gregg. Not a sign."

"I know. Our instruments here show that."

"There might be a way of sighting them," Drac put in.

"I'll try the Zed-ray," I suggested. "Drac and I have it corrected.
But I doubt if it would penetrate the sort of invisibility this enemy
would use."

Grantline nodded. "Or the Benson curve-light. You think the ship went
behind the Moon? Or landed on the Moon?"

"It could have done either. Has Waters still got contact with the
Earth? Have they seen it?"

"No."

I made a sudden decision. It would take us two hours at least to make
a careful scanning with the Zed-ray; and to take an elaborate series
of spectro-heliographs of the Moon's surface, which might show the
enemy vessel if it had landed there, was a laborious process.

After brief thought, I discarded the idea. "We'll go to the helio
room," I told Grantline. "I'm going to try the Benson curve-light."

Grantline